I have done some research on this subject, but I wanted to hear your personal thoughts. The boat model that I am fairly sure I will be purchasing, has sea water heads. I was actually thinking that the heads were fresh water until a broker brought this to my attention a couple of days ago.

I have heard that this type of system can be smelly. But, some say only if you don't use it. I was thinking that sparing the fresh water tank while on long passage or tied to a dock in winter could be a good thing, but not if that means stink. I cannot tolerate foul odors of any kind.

Wow never knew anything but a raw water head. Smelly ? well I guess if you are traveling in NJ waters or do not flush well or check after kids or drunks or just leave it stagnant. IF you really are conscious about smells that bad then a long cruise is going to make or break you.
You can pour a 1/10 a cup of your choice of " sure smells clean / good " every week of non-use if it really bothers you. My money is diesel and " what the hell is that " will over power that issue ;-)

traditional marine toilets except peeing overboard ar e salt water or whatever kind of water is under the boat.
some people dont like to have to flush long times to rid boat of inherent stagnant water smells when they dont use boat much, so they modify the toilet to be flushed with fresh water which is fine if yo9u stay at a dock and not have to ration your water to flushing toilet as well as other uses,.
my boat has traditional raw water manual flush toilet. no problems.

You will need to just try it and see before you can tell whether it will be a problem or not.

Raw water toilets have one huge advantage over fresh -- you can flush lots and lots of water through them to clear the very long discharge lines. Insufficient flushing is probably the number one cause of sewage system problems. You will not be nearly as willing to do so if your fresh water supplies are being depleted.

Electric toilets are also a big advantage in this regard -- it can be very laborious to flush through the required amount of water with a manual toilet.

All this may be moot if you are discharging into a holding tank, where the volume of the tank wil be a bigger limitation than your water supply.

I flush with seawater on my boat and there are never any odors, other than the first horrible flush after the boat has been unused for a few weeks.

I've had both types aboard a myriad of boats I've worked and lived aboard. If you are off shore and pumping overboard regularly, you can get by with raw water as a flushing medium but if you are in and out of port, using a black water tank, fresh is the only way to go IMHO. Having the ability to switch back and forth would only make sense if you periodically cruised and weren't tied to a dock regularly. The venting of heads and black water tanks is critical if you are re-working the system. Always opt for a larger diameter vent than is suggested. Make sure vent openings are remote from ports and passageways. All heads should be flushed clean with an agent like Simple Green before leaving the boat for more than a day or two.
For your purposes, GG, from what I have gathered it would be a good idea to replumb with fresh water. Raw water can get stinky quickly.
Dockheads observations and suggestions are sound if you opt for a raw water system but consider that you will be at the dock for long periods with access to fresh water so I would vote for fresh. Regards, Phil

Most boats are salt water heads. There is some truth to the need for use... to keep fresh salt water in the system instead of old water. if you are quite sensitive then maybe fresh water head is for you. If you have a good size water maker... no problem.

__________________"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard

If you use the toilet frequently you shouldn't have a problem. What causes raw water flush toilets to smell are sea flora and fauna (plankton and bits of seaweed) that are brought in with the water but get left in the rim of the bowl. The water drains out of the rim leaving these critters behind to rot. Daily use prevents the problem. If you're going to leave the boat for some time, flushing with fresh water before you leave will help but you've got to get it into the intake side. Just pouring a bucket in the bowl won't help.

Peggie Hall describes a method of connecting your head intake to the sink drain seacock. This allows you to close the seacock, run fresh water into the sink and flush the toilet.

You could also consider buying the boat you want, but taking the old plumbing out and replacing it with a composting head. This gets rid of all of your concerns, if you can just get used to doing things a little differently. No pumping, no through-hulls to worry about, no water leaks, no odor, no discharge issues in port, etc.

Biggest thing I notice w my raw water toilets is the bowl gets dirty where the water sits. The Raritan CP cleaner recommended for my Raritan Atlantes toilets dissolves the yuck on contact. I have a bilge fan that gets rid of all my bilge odors.

You could also consider buying the boat you want, but taking the old plumbing out and replacing it with . . .

One would never rationally choose or reject a boat on the basis of what kind of toilets it has, anyway. First of all, the cost of marine toilets is a rounding error compared to the cost of most cruising boats. Second, they usually need to be replaced anyway, or if they don't, they soon will.

So this is good advice -- buy whatever boat you want, and worry about the toilets later. Replace them with whatever you want if you don't like them. And remember you'll most like be replacing them anyway, even if you do like them.

Salt water flush heads usually only smell due to fouled/permiated raw water hoses, and not due to the clean salt water intake hoses unless you're in a marina with particularly foul water such as during a red tide.

Regarding fresh water head conversion idea: You would need a separate fresh water tank onboard dedicated to supplying only the heads. You can't take water from your primary fresh water tank and plumb it directly to the head, otherwise you'll risk contaminating your fresh water supply with sewage. Toilets on boats don't work like toilets in a house which always have positive pressure and a separate tank. Black water can and will contaminate the fresh water tubing if one neglects to install a proper one way, anti-siphon valve on a marine head. And because these valves can and do fail sometimes, the preferred method is to insall a dedicated fresh water tank in order to prevent this from ever happening.

I agree with Stu: Find everything that Peggy has written and pay attention to it. I have only had one issue with her advice (on aluminum tanks). If you are in US marinas and ports you will be required to have a holding tank. Replace all of the hoses with good (read expensive) ones and clean it well.

Make sure that you run lots of water through it and do the proper maintenance and there should be no problem.

We recently installed a Raritan Sea Era electric head with sea water flush. It came with an intake water filter, which I installed per instructions. The water in the bowl is always clean and odor-free, even if we're away from the boat for several weeks. And we are in muddy, South Carolina marsh water.

I had thought of going to fresh-water flush when we installed this system. But now I'm glad I stayed with sea-water.